Ink casettes, used in typewriters and/or printing units for word processors or computers and the like, whether or not provided with an ink reservoir for the ribbon, are usually replaced entirely. However, this procedure is expensive in practice, since a construction still per se of value is thrown away even when the print blackness of the ribbon is no longer satisfactory. Also unnecessary pollution of the environment results.
With an ink cassette according to the present invention, the spools and the ribbon can be replaced. If required, the entire cassette can also be replaced.
The following references from the prior art do not disclose an ink cassette according to the present invention and/or preferred embodiments thereof:
U.S. Pat. No. 4,687,357 (KATSURAGI et al.); PA1 U.S. Pat. No. 4,720,202 (KAWAKAMI, MASANORI); PA1 U.S. Pat. No. 3,990,563 (ADAMAK et al.); PA1 U.S. Pat. No. 2,257,553 (J.A. HEPT); PA1 -JP-A-60/011386 (KOUICHI TAKEDA).
Usually, a printer or typewriter is provided with a shaft driven in one direction only. According to the preferred embodiment of the invention the transport direction of the ribbon is changed automatically at the end of the ribbon, whereby efficient use of the ribbon can be achieved.
The preferred embodiment provides a cost efficient cassette because most parts thereof can be made of plastic material, yet nevertheless provide a good strength and stiffness for the operation of the cassette.
Further advantages, characteristics and details of the invention will become clear with reference to the accompanying drawings.